The Collaborative International Dictionary of English v.0.48:

Muddiness \Mud"di*ness\, n.
   1. The condition or quality of being muddy; turbidness;
      foulness caused by mud, dirt, or sediment; as, the
      muddiness of a stream.
      [1913 Webster]

   2. Obscurity or confusion, as in treatment of a subject;
      intellectual dullness.
      [1913 Webster]

WordNet (r) 3.0 (2006):

muddiness
    n 1: the wetness of ground that is covered or soaked with water;
         "the baseball game was canceled because of the wateriness
         of the outfield"; "the water's muddiness made it
         undrinkable"; "the sloppiness of a rainy November day"
         [syn: wateriness, muddiness, sloppiness]
    2: a mental state characterized by a lack of clear and orderly
       thought and behavior; "a confusion of impressions" [syn:
       confusion, mental confusion, confusedness, muddiness,
       disarray]
    3: the quality of being cloudy [syn: cloudiness, murkiness,
       muddiness]